Alloy



Feb 10, 1942. E. A. ANDERSON ETAL 2,272,392

ALLOY original Filed Jan. 16, 1940 '5 sheets-sheet 1 MYAVYAYA N.AYmmIes A VAVAYXAWA Aw-.LAYAYAYAVAVA 511g VYAVAVA A. A 1 3 z fiwmvmmv (bp/oer ATTORNEY Feb; 10, 1942. E. A. ANDERSON ETAI. 2,272,392

' ALLOY original Filed Jan. 1e, 1940v 3 sheets-sheetz 7a (bp/0er JMPA cr rif/Vaima ATTORNEYS Feb. 1.0, 1942. E. A. ANDERSON ETAL, 2,272,392

ALLOY Original Filed Jan. 16, 1940 3 Sheets-Sheet 3 AYQAVAVAYA AVAvaXVV/AA VVAVYVVA 40 AYQVAVAVAWAVA IHa@Amann VAVVAVYAVAVA WWAVVWAVAYVAVA VVAYVAYVVA v ,3f/WWW v i v f7@ ,LA g

v/AVAV zo HAYA. mmvnmxm v vnmm f im INVENTOR Edna/m A ndern?? Gerald dwz/m17:

` ATTORNEYS Patented Feb. 10, 1942 ALLOY Edmund A. AAnderson and Gerald Edmunds, Palmerton, Pa., assignors to The New Jersey Zinc Company, New York, N. Y., a. corporation of New' Jersey Original application January 16, 1940, Serial No. 314,086. Divided and this application July 22, 1941, Serial No. 403,568`

(Cl. l5-178) 9 Claims.

This invention relates to zinc base alloys and provides new alloys containing zinc, manganese, and aluminum copper and iron and having su` perior mechanical properties. The alloys of -our invention have an appearance similar to that of white metal alloys.

This application is a division of -our co-pending application Serial No. 314,086, filed January 16, 1940. f

As a result of our investigations, we have discovered new zinc alloys containing certain proportions of manganese, aluminum, copper and iron which, as cast, have an impact strength of about one foot-pound per one-quarter square inch cross section or more, a tensile strength of about 60,000 pounds per square inch or higher, and high creep resistance. They may be formed into intricate shapes of accurate configuration by die casting, and are also amenable to cast'- ing by other methods.

All percentages given hereinafter are percentages by Weight, and on this basis the alloys of, our invention contain aluminum in proportions ranging from 0.02% to about 5% (but preferably from 0.1 to 2%), together with manganese in the proportions ranging from about 7.5% to about 48.5%, and (preferably) copper in eiective proportions not exceeding about 261/2%, the balance of the alloy -being principally zinc, eX- cept that the alloys may contain a substantial percentage of iron. The proportion of iron which may be present is dependent upon the copper and manganese contents, but in general the alloys should not contain more than about 6% of iron. l

In. the manufacture ofthe alloys of our invention, it is not essential in all cases to employ high grade manganese, for the impurities lthat may occur in the ordinary commercial grades of manganese may be included in our alloys in some cases without too serious effect upon the properties thereof. Manganese suitable for use in the practice of our invention may contain minor proportions of silicon, phosphorus, carbon, nitrogen, and other impurities;Y We [prefer, however,l to use manganese of high purity, since impurities in the manganese may degradev 4the mechanical properties of the alloy and, in

particular, cause the presen e of hard particles that may interfere with machining and buiilrig.v The alloys of our invention, their composi` tion, and their mechanical properties, particularly in cold chamber die-cast form, are de? scribed more fully-hereinafter with reference to the accompanying drawings, Figs. I, 2, and 3,

which are trilinear charts representing the zinc corner of the Zn-Cu-Mn system, extending to J30% Gu and 50% Mn and in which:

Fig. 1 shows the approximate proportions of zinc, copper and manganese to be employed (together with certain proportions of aluminum and iron) in the manufacture of alloys of our invention having impact strengths of about 1 foot-pound or more per one-quarter inch square cross section; (In the specification and claims the term impact strengthrefers to values obtained in a Charpy impact test on unnotched test bars), and tensile strengths of about 60,000 pounds per square inch or better;

Fig. 2 shows the impact strength of the alloys bymans of contour lines; and

Fig. 3 shows the Brinell hardness numbers of certain alloys of our invention.

In Fig. 1, the contour line A' demarcates the range of composition in which the alloys have a tensile strength of 60,000 pounds per square inch or better. The contour line B' demarcates the range of composition in which the alloys have a tensile strength of 70,000 pounds per square inch or better. closes the range of composition in which the alloys have -a tensile strength of 80,000 pounds per square inch or better. TheV contour line D encloses the area in which the alloys have a tensile strength of 90,000 pounds per square inch or better. The dotted line E', E, E" is the saine as the line E', E", E" in Fig. 2, and encloses the range of composition in which the alloys have an impact strength of 1 foot-pound or more per one-quarter inch square cross-section. Then curved portion E' of this line is a contour line; the straight portions E" and E'" represent boundaries on the zinc-poor side of which difiiculties are encountered in the preparation and casting of the alloys. It will be noted that the contour lines A' and B do not\ enclose an area, being open towards the manganese corner of the diagram. Theline E'", however, closes the areas delimited by contour lines"` A', and B'. Thus, the area delimited by A' fand E" contains useful alloy compositions having a tensile strength of 60,000 pounds per square inch or better,y and the area delimited by B' and E" contains useful alloycompositions having a tensile strength ofr^.70,000 pounds per square inch or better.

In Fig. 2, the contour line E' indicates the range of composition of alloys having an impact strength of 1 foot-pound orvk more per onequarter inch square cross' section. As has been The contour line C' enexplained in the discussion of Fig. 1, the straight dotted lin'es `E" and E show limits beyond which towards the zinc-poor eld of alloy compositions d iculties are encountered in the preparation and casting of the alloys. Contour line F' indicates the range of 'composition of alloys having an impact strength of 2 footpounds or more per one-quarter inch square cross section. Contour line G indicates the range of composition of alloys having an impact strength of'4 foot-pounds or more per one-quarter inch square cross section. The areas, enclosed by contour lines F and G' are closed by the straight boundary E'". Contour line H encloses the range of'composition in which the alloys have an impact strength of 8 foot-pounds or more per one-quarter inch square cross section. Fo`r convenience of reference, contour line A and a portion of the boundaryline E'" are inserted in Fig. 3.

As shown in the trilinear charts, the proportions of copper and manganese are'interdependent in their effect upon the tensile strength and other properties of the alloys. The following tables give the approximate manganese range for specic copper contents (Table lI) and the approximate copper range for speciilc manganesef contents (Table II). As shown in Fig. 1, the contour A (drawn through points representing the composition of alloys having tensile strength of about 60,000 pounds) and the contour line E (drawn through points representing the composition of alloys having impact strength of` about 1 foot-pound per one-quarter-inch square bar) are roughly coincident and define approxlmately the same area. In short, the alloys of our invention have tensile strengths of about 60,000 pounds per square inch or more, together with impact strengths of about 1 foot-pound plus. 'I'h'e values in Tables I and II represent points on both contours A and E', dependingupon which is outermost on the chart. Thus, in order to obtain alloys that may be cast readily and that have, as cast, tensile strength of approximately 60,000 pounds per square inch or more and impact strength of about 1 foot-pound per one-quarter inch square section or more, the approximate manganese ranges for given copper contents are as follows:

To express `the relationship of copper and manganese contents in' another way, the approximate limits of copper content for given manganese contents are as follows:

TABLE II Per cent Mn Per cent Cu eeeaeaeea C As shown in Fig. 1 (Area A) an alloy of our invention containing 0.15%

aluminum, 38%- 48.5% manganese. and substantially no copper, the balance being substantially all zinc, has a tensile strength as cast of about 60,000 pounds l per square inch (points I0'|0"). The same tensile strength is found in alloys with the same aluminum lcontent but with various proportions of manganese and copper as follows:

Area "A Boundary Am A proximate analyses of alloys aving. tensile strength of v about 60,000 pounds per Point on Fig. l Square inch Percent Percent Percent Al Cu Mn Still, higher tensile strengths are obtainable by differently proportioning the manganese. and copper contents of the alloys of our invention.

' Certain of the alloys of our invention have, as cast, tensile strengths of about 70,000 pounds per square inch or higher. These alloys contain in addition to about 0.02% to about 2% aluminum, from about 1.5% to about 24% copper. and about 11% to about 48.5% manganese, th'e balance of the alloy (except fora relatively small iron content) consisting essentially of zinc. In thesealloys the copper and manganese contents are s0 related as to dene pointslying substantially in the area B" on the trilinear chart (Fig. 1).

Some of the.- alloys have, as cast, a tensile,`

strength of 80,000 pounds per ysquare inch or more and contain in addition to aluminum ranging from about 0.02% to about 2%, copper in proportions ranging from about 9% to about 22.5%, and manageneseranging in proportions from about 13.5% to about 34.5%', the balance of the alloy as in the previous cases consisting essentially of zinc, with a relatively small proportion .of iron, and the copper and manganese contents of the alloys being such as to define a point lying substantially in the area C on the trilinear chart (Fig. 1.).

To vobtain alloys having a tensile strength of about 90,000 poundsI per square inch or more, in accordance 'with our invention the aluminum content of the alloys should range from about 0.02% to about 2% and should be accompanied by manganese, in proportions ranging from about.15%` to about 221/2%, and copper in proportions rangingfrom about 15% to about 22%.

- those having a tensile strength of at least 80,000

pounds per square inch are those having copper and vmanganese contents that fall within the y area C on Fig. 1, while thoseof tensile strengths of 90,000 pounds or more per square inch are those having manganese and copper contents enclosed within the area D on Fig. l. For example,

those alloys containing 0.15% aluminum, 20% copper and 16% to 22.5% manganese, the balance being substantially all zinc, have tensile strengths of at least 90,000 pounds per square inch.

It will be bbserved that the range of` useful alloys having impact strengths of 1 foot-pound or more per one-quarter inch square section is defined by the area E, enclosed by the impact strength contour linel E onthe trilinear clrarts running from point (0% Cu, 33.3% Mn) through point 24 (16% Cu,'l0% Mn), point 14' (20% Cu, 7.5% Mn), point 25 (20.2% Cu, 10% Mn), point 26 (23% Cu, 20% Mn), point 27 (22% Cu, 25.5% Mn) to point 15" (25% Cu, 31% Mn) the straight line E running from point to point 28 (11% Cu, 44.5% Mn); and the straight line E" running from point 28 to point 10" (0% Cu,-48.5% Mn). The line E'" in addition to establishing part of the boundary of area E, marks the limit of areas A and B on Fig. 1, and areas F and Gon Fig. 2.

The straight lines E" and E are not contour lines, but, in the case 4of compositions lying substantially above or outside theselines, i. e., on the zinc-poor side of these lines, difficulties are encountered in the preparation and handling oi the alloys.

All of the alloys of our invention have, as shown in Fig. 2, adequately high impact strengths, that is to say, they are not brittle.

zinc -alloys at very low temperatures. Thus, an alloy of our invention containing 24% to 25% manganese, 15.2% to 15.5% copper, 0.15% to 0.18% aluminum (the remainder being special high-grade zinc of high purity) was tested for peratures and was found not to become brittle,

l even at temperatures as low as 40 C.

The area F enclosed by the contour line F on Fig. 2 indicates the proportions of copper and manganese employed in alloys of our invention, together with aluminum (the balanceof the alloy beingisubstantially all zinc) to obtain impact strengths ofat least 2 foot-pounds in a cold chamber die-bast bar with a one-quarter inch square section. Still higher impact strengths (i. e., 4 foot-pounds per quarter inch square'section, or better) are obtained with compositionsv falling Within the area G bounded by the contour line G on Fig. 2, and impact strengths of 8 foot-pounds per one-quarter inch square, or better,`are obtained with alloys of compositions fallingwithin the larea H bounded by the contour line H on Fig. 2.

Approximate limits of the several areas in terms of the copper and manganeser contentsV they represent are as follows:

Tensile strength, pounds Area Copper Manganese per Sq. 111. fange fange Percenf Percent A 0-26 8Vz48y B 1%-24 l1-48 C 9-22 .13%P l/ D 15-22 1522% Impact strength foot-pounds Ama Copper Manganese per% in. square range range E o- 7511-481@ F 0-23 l2-,48y G 0 2124 lai/48% H 'LV2-20 2(138 temperature embrittlement encountered in many Alloys of our invention have high creep resistance. Alloys containing 24-25% manganese, 15.2-15.5% copper, and 0.l5-0.18% aluminum, the remainder being special high-grade zinc, were tested for creep resistance at 25 C. under bending stresses equivalent to maximum ber stresses in tension up to 70,000 pounds per square inch. No creep was detected duringthree days. In contrast, heretofore customary zinc base diecasting alloys suffered detectable creep in three days under a stress of 2,500 pounds per square inch, other conditions being the same.

The modulus of elasticity of alloys of our invention as indicated by beam deflections observed during the above reported creep tests was found to be about 14,000,000 pounds per square inch, which is greater than that of any zinc base die-casting alloys kno`wn to us.

Moreover, the alloys` of our invention possess apparent rigidityL or stiffness to a degree greater than that of any lother zinc alloys of reasonable ductility.

All of the alloys of our invention are machinable.

The alloys of our invention manifest good resistance to atmospheric corrosion. Further, Water immersion tests of alloys containing 25% Mn, 15% Cu and 0.15% Al (the ybalance being substantially all zinc) lshowed a corrosion resistance roughly comparable to that of the zinc base die-casting alloys Nos. XXI, XXIII, and

XV of A. S. T. M. tentative specifications.

CryAlloy I Il 111 1V V y' Jl Analyzed percent Mn... 22:2 24. 7 29. 6 "34. 2 21.6 Analyzed percent Cu 17. 5 i 15.4 14. 4 v 10.0 18. 3 Analyzed percent A1. 0.15 0. 17 0. 18 0. 18 0. 14 Analyzed percent Fe.. 0. 17 0. 19 0.23 0. 28 0. i8 Tensile strength lbs. per

Sq. in 90,200 89,100 84,900 81,200 97,300 Tensile elongation, per- -L Y centin2in. Y 2 6 2 2 Impact strength, `footpound on :1% in. sq. v bar l 12.9 18 12,1 r11. 9 12. 7 Brinnell hardness numbei' 167 158 161 159 184 It will be observed that the al/loys lying within the preferred range possess, as cast, remarkably superior characteristics which favor their use in the manufacture of a great variety 'of 'articles ,by inexpensive processes, such as die casting.l A AAs indicated hereinbefore, aluminum/[is an essential ingredient in the alloys of our invention. ,The presence of the aluminum not only improves the casting characteristics of the al- 1oys, but also tends to suppress oxidation of the surfaces of the hot casting. The presence of the aluminum in the alloys of our invention enables castings made thereof to be cooled in air without serious discoloration. An unsightly brown film forms on the surface of air-cooled castings of similar Zn-Cu-Mn alloys without the aluminum. Moreover, the presence of the aluminum in the alloy within the range specified, i. e., 0.02% to about reduces dross formation on the molten alloy during casting operations and tends to impart an attractive silvery appearance to the resulting casting. When aluminum is not present, a tenacious brown lm tends to form on the molten alloy, interfering with pouring and making diilicult the production of a casting having a smooth surface. However, an aluminum content of more than about 5% cannot be tolerated because of the deleterious effect thereof upon the mechanical properties of the alloys. In case the aluminum content exceeds 2%, the tolerance for impurities is limited. The effect of aluminum upon relatively impure alloys is illustrated in the following table:

Alloy VI VII VIII IX Analyzed percent ol Mn 24. 7 24; 7 23. 8 2l. 5 Analyzed percent of Cu 15. 4 15.4 15.4 13. 3 Analyzed percent of A1- 0. 023 0.45 1. 2 5. 3 Analyzed percent of Fe 0. 19 0.21 0. l0 0. 2l Tensile strength, lbs. per square Y inch 90, 600 86,100 89, 200 28, 700 Tensile elongation, percent in 2 in 5 2 1 Impact strength, foot-pounds on M in. sq. bar 16y `1l 3.1 0.4 Brinell hardness number 166 172 191 214 The inclusion of up to 6%` iron in the alloys'ofl our invention is permissible. The tolerance for iron of the particular alloy depends upon its copper and manganese and impurity contents and is greater for some compositions. The effect of the inclusion of iron upon relatively impure alloys is shown by the following data:

'Not analyzed. synthetic composition, 0.15% Al.

The inclusion of iron, however, is not essential A in all cases, and alloys of our invention similar to those described herein but without iron are dei scribedand claimed in our aforementioned copending application.

All of thespeciiic alloys described herein'were made from zinc having a purity of at least 99.98%. v

'I'he alloys of our invention can be prepared with the ingredients charged into the crucible in the form of unalloyed metals or alloys 'of these with each other.

We have found clay-silicon carbide and castv iron We prefer to melt the alloys in a crucible substantially nonreactive to the-alloys.

crucibles to be satisfactory. It is helpful in many cases to protect the surface of the molten alloy with a nonreactive gas, e. g., hydrogen.

As indicated hereinbefore, all of the alloys of our invention can be die cast and offer certain advantages over heretofore customary zinc alloys lthat can be die cast because of their greater strength and hardness. However, certain alloys of our invention have been gravity cast in permanent metal moulds and also gravity cast in sand moulds. Although some differences in properties of the alloys of our invention are induced by the method of casting, the alloys of our invention in general exhibit superior properties as compared with heretofore customary zinc alloys, irrespective of the particular method of casting.

We claim:

l. An alloy containing about 0.02per cent to about 5 per cent aluminum and about 7.5 per cent to about 48.5 per cent manganese, substantially all of the balance of the alloy being elements selected from the group consisting of zinc, copper and iron, the copper being present in effective amount up to about 26.5 per cent and the iron being present in effective amount up to about 6 per cent, the copper and the manganese contents of the alloy being such as to define a point on the accompanying trilinear chart (Fig. 1) lying within an area defined by a line connecting'the following series of points:

Point No. Percent Cu Percent Mn seesassssssssaafs D172@ 2. alloy having as cast an impact strength of at least about 1 foot-pound per 1A inch square section andcontaining about 0.02 per cent to about -5 'per cent aluminum, copper in effective amountup to about 26 per cent, iron in effective amount u'p to about 6 per cent and about 7.5 per cont to about 48.5 per cent manganese, the balance of the alloy being substantially all zinc and the copper and the manganese contents of `rthe alloy being so related to each other as to deflne a point on `the accompanying ltrilinear chart (Fig-2i lying within the area E defined by the line connecting the following series of points:

Point No. Percent Cu Percent M n 0 33. 3 16 l0 m 7. 5 l). 2 l0 23 I) 22 25. 5 25 3l 1l 44. 5 0 48 5` 0 33. 3

within the area. IjI dened by the line connect- 3. An alloy having as cast an impact strength of at least about 2 foot-pounds per 1/4 inch square section and containing about .0.02 per cent to about 2 per cent aluminum, copper in effective amount up to about 23 per cent, iron in effective amount up to about 6 percent, and manganese in proportions ranging from about 12 per cent to about 48% per cent, substantially all of the balance of the alloy being zinc, the copper and mangancse in the alloy being so related to each other as to dene a poin't on the accompanying 'trilinear chart (Fig. 2) lying within the area F defined by the line connecting the following series of points:

Per cent Cu Per cent Mn 4. An alloy having -as cast an impact strength of at least about 4 foot-pounds per 1/4 inch square section and containing about 0.02 per cent to about 2 per cent aluminum, copper in eiective amount up to about 211/2 per cent, iron in eiective amount up to about 6 per cent, and about ll/2V per cent to about 481/2 per cent manganese,

substantially all of the balance of the alloy be` ing zinc, the copper and manganese contents of the alloy being such as to define a point on the accompanying trilinear chart (Fig. 2) lying within the area G dei-ined by the line connecting the following series of points:

Per cent Cu Per cent Mn 5. An alloy having -as cast an impact strength section and containing about 0.02 per cent to about 2 per cent aluminum, about '7l/2 per c ent to about 20 per cent copper, iron in eiective amount up to .about 6 per cent, andabout 20 per cent to vabout 38 per cent manganese, sub-` stantially all of the balance of the alloy being zinc, and the copper and manganese contents of -V the alloylbeing so related as to define a point on the accompanying trilinear chart, (Fig. 2) lying of at least about 8 foot-pounds per 1A inch square.

ing the following series of points:

Per cent Cu Per cent Mn l 6. An alloy having as cast a tensile strength of at least about 60,000 pounds per square inch and containing about 0.02 per cent to about 5 per cent aluminum, copper in eiective amount up to about 261/2 per cent, iron in eiective amount up to about six per cent and about 81/21per cent to about 481/2 per cent manganese, substantially all of the balance of the alloy being zincv and the copper and manganese contents of the alloy being such as to dene a point on the accompanying trilinear chart (Fig. 1) lying within the area A dei-ined by the line connecting the following series of points:

Point No. Per cent Cu Per cent Mn 7. An alloy having as cast ay tensile strength of lat least about 70,000 pounds per square inch Per cent Cu Per cent Mn 8. in alloy having as cast a tensile strength of at least about 80,000 pounds per square inch and containing about 0.02 per cent to about 2 percent aluminum, about 9 per cent to about 221/2 perv cent copper, iron in effective amount up to about sixper cent, and about'131/2 per cent to about 341/2` per cent manganese, substantially all of the balance of the alloy being zinc and the copper and manganese contents of the alloy being such as to define a point on the accompanying trilinear chart (Fig. 1) lying within the area C" dened by the line connecting the following series of points:

Per cent Cu Per cent Mn 9. An alloy having cast a tensile strength of at least about 90,000 pounds per square inch and containing about 0.02 per cent to about 2 per cent aluminum, -about 15 per cent to about 22 per cent copper, iron in eiective amount up to about six per cent and about 15 per cent to about 221/2 per cent manganese, substantially all oi the balance of the alloy being zinc, and the copper and manganese contents of the alloy being such as to dene a point lying withlnthe area D" on the accompanying trilinear chart (Fig. 1) delineated by the line D' passing throughthe following series of points:

Per cent Cu Per cent Mn vIElDMUND'AYi. ANDERSON. 'GERALD EDMUNDS. 

